The Yancey Threader* is a portable threading attachment that can be used on a lathe or other machines to thread any metric or English threads.  It is machine operator friendly.  Although it technically is a CNC, it has no CRT display, keyboard, or programming language.

The threading process on a manual engine lathe is made easier with the Yancey Threader.  Both English and metric thread leads, any lead, can be cut.  Threading to an exact end point on every pass (up to a shoulder for example) is very useful and safe.  And automatic return to the thread start point without worrying about bumping the tailstock gives the operator time to think about the next pass.  There is no waiting for the thread dial to come around before you can take your next pass.  No hassle with getting half nuts engaged or disengaged.  Just press Start and the threading tool takes off.

 The Yancey Threader is made up of these components: a control box, portable electrical cables, a spindle encoder, tool slide, and an operator pendant.

The Yancey Threader generally mounts to a lathe compound and provides Z axis in lead movement of the threading tool.  The lathe needs an encoder mounted to the spindle.  There are several ways to mount the encoder.

            There is a control box with a servo motor drive and a PLC inside.  The power cord and other cables attach to this control box using MS Connectors.

Two sets of thumbwheel switches on the lid of the control box provide a means for the operator to set in the thread lead to 5 decimal places, and to set parameters for how the attachment is to be used. 

The operator’s pendant has 8 push buttons, a feed rate potentiometer, a mode switch, feed rate display and position display.

The threader can be used to do the pre-threading operations of feeding the turning / facing tools, or boring tools commonly used before the threading operation.  In FEED mode the tool can feed from a very slow federate to 40”/min.  The feed potentiometer is continuously variable over this range and can be varied during the cut.  The operator could choose to use the threader as only a tool holder and use the saddle and compound as it is normally used for pre-threading operations.

When threading, the saddle needs to be locked and the threader slide provides the in-lead movement.

The threader can generate tapered threads without the use of a taper attachment.  (If the lathe is equipped with a taper attachment it is not used.)  The lathe half nuts and lead screw are not used when using the Yancey Threader.

The Yancey Threader can be used as a portable machine to turn and thread in the field.

The Yancey Threader can be used as a portable machine to turn and thread in the field.  A shaft in a big machine could be turned and threaded in place if there is some minimum access.  This would save time and money rather than take the machine apart and transport the shaft to a machine shop.

The Yancey Threader can be used for many in lead operations besides cutting threads.  Examples are:  spray welding in lead to build-up a shaft, wind a shaft with epoxy material to give it a uniform coating of fiber/epoxy.

Example procedure for cutting external threads:

            Set the lead using the thum bwheel switches on the control box.

            Placed the threading tool in the threader tool holder and adjust the tip for proper center line height.

            Move the tool tip to the thread start point using the JOG mode with the IN and OUT push buttons or select the MPG 1 or MPG 2 mode and use the MPG handle to position the tool tip.  Move the tool to the thread start point, 1 lead off of the end of the shaft or socket to be threaded and press the INIT POS (initial position) push button.  The INIT POS button will then light. The control in effect memorizes this initial position. 

            Move the tool tip to the end of the thread position by using the JOG mode or MPG modes. then press the thread END POS push button.  The control in effect now memorizes the thread end position and the END POS lamp will light.  Now pressing the INIT POS push button, will cause the threader slide to automatically bring the tool tip back to the INIT POS and the INIT POS push button lamp will blink to indicate the tool is at the home position.

            Start the lathe in the appropriate threading RPM and engage the headstock so the work is turning.  Now pressing the START push button will initiate threading.  The control will wait until the spindle marker pulse is registered and the tool will quickly be accelerated to the proper threading speed and will continue in lead until the end point is reached.  Once engaged, the tool movement is tied to the spindle movement in an electronic gear ratio.  If the spindle speeds up or slows down the threading tool position will stay in lead.  Even if the lathe stops, the tool will stop movement in lead.  Even if the spindle is taken out of gear and manually rotated backwards, the tool will track with this spindle movement.  This feature can be used for “picking up a lead” which is necessary for repairing an existing thread.

            The lathe operator is responsible for “pulling the tool out of the cut” just as it reaches the thread END Position.  To help the operator, a Sono-a-Lert beeper is set to beep a set number of leaders before the END POS is reached.  The operator can get ready and move the compound (tool) out of the cut as soon as the beeper sounds. 

The mode switch on the operator pendant has 2 kinds of threading.  “THREAD INIT” causes threading where the tool is returned as soon as it reaches the END POS.  In this mode the operator must pull the tool out as soon as the beeper is sounded, so the work piece will not be cross threaded while the tool rapids back to the initial point.

            The other threading mode is marked “THREAD EP.”  In this mode the threading will stop at the end point.  The operator still must “pull the tool out” using the compound or cross slide as soon as the beep is heard, but if the tool is threading into a thread relief or off of the part, the pull out timing is not so critical as the tool will not travel back to the initial position until the operator presses the “INIT POS” button. 

            Then the next pass depth is set using the compound and/or the cross slide and the “START” push button is pressed to start the next threading pass.  And so on until final thread depth is reached.  It is good practice to take a spring pass or two at final depth. 

One place the Yancey Threader really works well is on internal threading. 

One place the Yancey Threader really works well is on internal threading.  Internal threads are done with a threading boring bar blind.  And some internal threads are made right up to an inside shoulder, so with conventional threading if the operator is late getting the half nuts open, the part and the tool will be crashed and it will be hard to save the part, the tool, and the machine may be damaged.  

The Yancey Threader stops every time right on the END POINT.  You can dither the start point + or – to cut on the slides of a thread or to do multi lead threads (like in Acme threading) but the end point will always be in the same place.

Doing a left-handed thread is no problem with the Yancey Threader.  The initial point would be toward the headstock and the end position would be towards the tail stock.  The L.H. thread would generally need a thread relief at the INIT POS and threading to the END POS could be to a shoulder or off the end of the part.

If you needed to thread from the tailstock end towards the headstock, you would need to run the spindle CW (Backwards) and hang the threading tool upside down.

Threading Helps:

1.     Have a threading plan.  Plan your depths of cuts before you start up the lathe.

2.     For CNC canned cycle like threading, the tool is moved on the inverse square root of the number of passes requires, plus 1 or 2 spring passes.  For example if you think 6 passes would do the stock removal and 2 spring passes to finish, the threading plan would look like this:

First pass of 6 passes 1/ SQ ROOT 6  =.408 = 40.8% of Ds (thread depth on a side)

Second pass. 5 passes remaining 1/ SQ ROOT 5 = .447 = 44.7%

Third pass, 4 passes remaining 1/ SQ ROOT 4  = .500 = 50%

Fourth pass, 3 passes remaining 1/ SQ ROOT 3  = .577 = 57.7%

Fifth pass, of 2 passes remaining 1/ SQ ROOT 2 = .707 =70.7%

Sixth pass, of 1 pass remaining 1/ SQ ROOT 1 =1.000 =100% (Full depth of cut on a side.

3.     If you are threading a standard thread, don’t use an “up sharp” insert.  The tip is the weakest part of the insert and heat going into a sharp tip is not well dissipated.  Use an insert with as much flat (max. 1/8 Lead) as the nut will allow.  For fine threads, like bearing nut threads up to 18 TPI, a sharp insert is ok.  But for coarser threads try to use the most thread flat that works.

4.     If the material is gummy and the nut won’t go on so well and you are at the right thread depth, don’t just go deeper.  Try lapping the nut on with Time Saver Lapping Compound.  The ash (glass) particles in Time Saver find the hairs and tight spots and quickly cut them down and at the same time the glass particles of the Time Saver break down smaller and smaller until it is just mud and has no real cutting ability.  It is surprising how fast a bearing nut can be fitted and not be sloppy.  Forcing the bearing nut will only gall the thread.  Time Saver is not emery.  Emery should not be used for this kind of lapping.

5.     It is a good idea to set in the lead using the thumb wheel switches, INIT POS, and END POS then take an air pass just to see that everything is set up correctly.  Then, on the way back to the INIT POS, move the tool in to just touch the diameter to get your zero point for your compound or thread dial. It will also work to set your dial and thread stop device just after you establish the INIT POS and are on the way to set in the END POS. A magnet base indicator with 1” travel in .001” is helpful to set your zero point on your compound or cross feed dial so you can easily return to the “right zero” on each pass.  There are also inexpensive digital scale readouts that can be mounted on the lathe compound to help with this job.  They have a 1 meter wire from the scale to the display so you can mount the display in a convenient location. (Bag the readout in a clear plastic bag to keep the readout clean and dry.)

THREADING A BRONZE NUT

     When threading a bronze or brass nut for something special like a cross feed screw or compound screw it is important to have as little backlash as possible.  Bronze or brass laps easily with Time Saver so stop threading when the screw just starts in the nut but seems tight.  Lap the nut in with Time Saver.  The glass particles (ash) in the Time Saver brake down to a point where they are not abrasive, they do not embed in the brass and ware the screw out like Emery would.

If you have threaded to depth and the nut will not go on nicely it may be the threading holder or insert in the threading holder is not square with the work piece.  Slight thread profile mismatch can be fixed by Time Saver lapping - not by just threading deeper.  Threading deeper just makes a sloppy fit with compromised thread strength.

The Yancey Threader technology can be applied to custom machines or to retrofit standard machines that have no theading.

The Yancey Threader comes in several slide types and lengths.  Generally an Aloris Tool post (customer supplied) is mounted to the saddle of the Yancey Threader and individual Aloris tool holders are set up so the tool tips are on center line of the axis of the lathe.  Each of the following tools can be used in the Yancey Threader:  A ruffing tool for rapid stock removal, a finishing tool to get the proper major diameter (in the case of an external thread), a grooving tool (if a thread relief is needed), and a threading tool.  Each tool should be pre-qualified at least for height. 

The Yancey Threader can be set up with 2 tools mounted to the threader saddle; one for turning and facing and the other for the threading.  This eliminates tool changes for more production.  In this case, a special tool block would be required and replace the Aloris type tool post system.  

The Yancey Threader technology can be applied to custom machines or to retrofit standard machines that have no threading.  It can be incorporated into VBM machines, like Bullards, enabling them to cut threads.  (Both inch or metric).  The Yancey Threader technology can be added to the VBM ram or side head as a custom job.  The Yancey Threader technology can be incorporated into a welding positioner to build up worn threads for re-cutting.  The sides of these large threads can be built up on successive welding passes with the wire feed welder adding material automatically in lead.  An example would be for large rock crusher parts.   

In some cases on a lathe there may be a need for a long reach turning/threading slide.  For example to reach out in front of the saddle to turn and thread the end of a cylinder that reaches clear to the bed ways.  The Yancey Threader technology can be applied to a long reach compound tool slide.

The Yancey Threader most often uses Gilman Slide components that are modified to receive end brackets that support the 10 TPI by 1” diameter acme lead screw and the servo motor.  The feed nut is made from Vasonite plastic and lubricated with grease.  The long Vasconite nut is tapped with a long precision tap for a strong low backlash fit.  The saddle slide has been drilled for lubrication and should be lubricated with way oil.  The screw and nut are mounted above the saddle because the slide needs be thin enough to both sit on the compound and get the cutting tool tip on center line. 

Questions

Q.  If there is a power outage will my threading place be lost? 

A.  The rotational start point for the thread is fixed in the encoder and is the same even when the power is off and then on again.  The INIT POS stored in the controller is lost with power off and on.  However the battery-powered threader axis display will still be correct when the power is off then on.  It will be necessary to confirm the tool is in the same INIT POS before continuing threading.  It is always a good practice to zero the axis display when first establishing the INIT POS.  The END POS will need to be re-established if there is a power failure so one would be wise to record the END POS number from off of the axis display when first establishing the END POS. 

Q.  If I want to move in on my thread at 29.5° can I still use the Yancey Threader? 

A.  YES.  When moving in at 29.5° or 30° using the compound set to these angles the Yancey Threader must be mounted on the compound parallel to the center line of the lathe (unless you are cutting a tapered thread).  The total thread depth using the dial on the compound when the compound is set at 29.5° increases by 15.5% or multiply Ds (Depth of thread on a side) by 1.1547. 

Q.  Can I cut tapered threads, like pipe threads, with the Yancey Threader since it does not use the taper attachment? 

A.  YES.  For tapered threads the Yancey Threader is mounted on the compound at the desired angle and the tool in the tool post must be 90° to the center line of the lathe, not at 90° to the threader axis.  The lead value put into the thumbwheel switches must be increased.  Example:  A pipe thread of 8 tpi, with a 3/4” change in diameter per ft. = 3/8” / 12” taper on a side.  3/8” / 12” = .375 / 12” which equals .03125 and the tan-1 of (.03125) gives an angle of 1.78991 deg., then the COS of 1.78991 deg. Is .999512 and the inverse (1/.999512) = 1.00048812 so when threading along this taper the operator would need to increase the thread lead by a factor of 1.00048812.  8 threads per inch has a normal lead of .125” for straight threading but for this taper the lead would be .125 x 1.00048812 which is .12506.  This is the lead that would need to be input into the thumbwheel switches.  See the appendix for more explanation. 

Q.  Can I cut 2 start threads with the Yancey Threader? 

A.  Yes.  Single, 2, 3, 4, 5 and maybe more starts can be cut with the Yancey Threader.  For example, for a 2 start thread, after cutting the first lead, move the Start point, the INIT POS, ½ of a lead using the digital axis display and thread again.  The end position will not change, but the thread will start 180° later.  Use the same idea for other multi start threads.  For 4 starts, move the start point (INIT POS) over ¼ lead for each start.  Use the MPG mode and the digital display to move the start points exactly the right amount for each lead. 

Q.  What if I break an insert while threading? 

A.  You would want to stop threading by first pulling the tool out of the cut with the compound or cross slide.  Then you could stop the feeding in lead by pressing the STOP button and you can return the tool to the initial point by pressing the “INIT POS” button.  Stop the spindle.  Change the insert and continue threading but maybe back off a pass or two.  Make sure any broken carbide is out of the thread before using the new insert.

Q.  Why doesn’t the Yancey Threader have an HMI interface with touch screen but only has push buttons and a hard-wired pendant?  

A.  The pendant is rugged but if damaged it is easily repaired or replaced.  HMI interfaces are made for only a year or 2, then their production is replaced by the manufacturer by a better one, that typical is smaller, costs less, (more cheaply made) has more features—but needs to be re-programmed by a programmer.  The old program would need to be translate into the new format or at a minimum the old program loaded into the new HMI control.  This requires someone with these skills and a recorded program to do this work.  A button on an HMI interface can’t be replaced—generally the whole unit is replaced.  The machine shop environment is generally too dirty and rough for successful HMI use.  (Here I am using HMI to describe a pendant box with a screen, membrane  push buttons or touch screen buttons, and contains a CPU and communicate by serial data or wifi.  The use of an HMI on the Yancey Threader is possible and may be suited for some niche applications.)

Parameter Settings

The large thumb wheel switch on the control box cover is for setting in the desired lead for threading, etc. The lead is put in as one integer and a five place decimal fraction.  (x.xxxxx)  8 threads per inch = 0.12500 lead if the compound is straight on, 0 deg. 

The smaller thumb wheel switchs are used for setting in operational parameters. 

There ae 5 digits on the small thumb wheel switch, each displays 0-9.  These digits are BCD coded so there are 4 possible electrical contacts: 1,2,4,8 that signal the position of the thumbwheel switch to the controller to set set in a particular parameter.

Switches may be set 1 through 0 but generally 0 to 3 is used to set in the desired parameter value.

The thumb wheel on the right is #1, and it can be set to 0 through 3 to set the maximum jog rate.

Thumb wheel #1 can be set to 0, 1, 2, or 3.

            0= 30’/min.       max jog rate

            1= 60”/min.      max jog rate

            2= 120’/min .   max jog rate

            3= 180”/min. .  max jog rate

Thumb wheel #2  can be set to 0, 1, 2, or 3 and is used to set in the one revolution count rate of the spindle encoder according to type and mounting.

            0= 1024  Encoder type in pulses Per revolution

            1= 2000  “

            2= 2500  “

            3= 5000   “ 

 Thumb wheel switch #3 can be set to 0, 1, 2, or 3 and it is used to set into the controller the number of leads before the END POS where the beeper will sound.

            0= 1  One lead before the END POS

            1= 2  Two leads before the END POS

            2= 3  Three leads before the END POS

            3= 4   Four leads before the END POS

Note:  Finer threads need more warning time for pull out reaction time.

Thumb wheel #4 can be set to 0, 1, 2 or 3 and is used to set spindle rotation with IN / OUT direction.

            0= ccw  Spindle encoder direction, IN / OUT  push buttons normal

            1= cw    Spindle encoder direction, IN / OUT  push buttons normal

            2= ccw   Spindle encoder direction, IN /OUT  push buttons reversed

            3= cw   spindle encoder direction, IN / OUT push buttons reversed

Spindle Encoder Direction 

This parameter, smaller thumb wheel switch # 4, is used to signal the controller which direction the encoder is rotating and which direction the spindle is turning and which way the IN and OUT push buttons move the threader slide.  If the encoder is mounted at the rear of the lathe directly to the spindle tube by a sort of plug or if it is belted from off the spindle tube, the spindle encoder rotation will be normal, both rotating the same direction.  If the encoder is mounted to a gear that revolves in synchronization with the rear spindle tube, the spindle encoder rotation will be reversed from the spindle’s, therefore this parameter will need to be set to a value that reflects spindle encoder rotation is reversed. 

When a spindle encoder is belted so that its shaft is pointed to the back of the headstock it is necessary to set parameter #4 to a value of 1 or 3 depending on

how the operator wants the IN and OUT push buttons to move the slide.  The Yancey Threader could be mounted parallel to the chuck face for face threading or pealing and the meaning of IN and OUT pendant push buttons would need to be changed using parameter #4. 

When the Yancey threader is setup with its axis parallel or nearly parallel to the long axis of the lathe IN means into the chuck, towards the chuck (headstock).  OUT means out away from the chuck, towards the rear of the lathe, towards the tail stock.

When the Yancey Threader is setup with its axis at 90 deg. to the long axis of the lathe IN means into the center of rotation and OUT means out away from the center of rotation, out to a bigger diameter.  This is the case where the Yancey Threader is set up across the face of the chuck for face threading or pealing. 

The spindle encoder electronic signals could be reversed electronically which would flip the meaning of the above spindle encoder direction parameters also.  

Thumb wheel switch #5 can be set to 0 or 1 and is used to set the direction of the MPG hand wheel for the + direction, to make the handle “feel right”.

     0 = cw rotation of the MPG handle causes the Yancey Threader slide to move in a plus direction.                               

      1= ccw  rotation of the MPG handle causes the Yancey Threader slide to move in a plus direction.                              

For more information contact:

Byron Yancey

Yancey Machine Tool Co.

4110 S.W. Macadam Ave.

Portland, Oregon 97239

phone 503 228 7259

email YMT@safeaccess.com

* patent applied for US Patent office # xxxxxxxxxxx

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